Jerry McCrea/The Star LedgerU.S. Attorney Paul Fishman (right); announces a Department of Justice investigation into Newark Police Department, based on ACLU's petition last year alleging rampant misconduct in the Department; during a press conference held at the offices of the US Attorney in Newark . Listening are Cory Booker, Mayor of Newark (left); and Thomas E. Perez, Assistant Attorney General for the Civil Rights Division of the Department of Justice.

CHICAGO — Mayor-elect Rahm Emanuel's transition team is reacting to the news that his choice to be Chicago's new police superintendent is leaving a New Jersey department under federal investigation.

The Justice Department today announced it was investigating policies and practices at the Newark police department. Earlier this month, Emanuel named Newark Police Director Garry McCarthy as his choice to be superintendent. Emanuel's pick still needs formal approval from the Chicago City Council.

Emanuel's team said in a statement that McCarthy instituted "aggressive and successful reforms." They also say McCarthy asked the Justice Department to work with Newark to study its reforms.

The Justice Department won't say why they initiated the investigation.

The American Civil Liberties Union had complained of rampant misconduct and lax internal oversight at the department.